Understanding the relationship between a protein's amino acid structure and its overall function continues to be of great practical, clinical, and scientific significance for biologists and engineers. Directed evolution can be a powerful engineering and discovery tool, but the random and often combinatorial nature of mutations makes their individual impacts difficult to quantify and thus challenges further engineering. More systematic analysis of contributions of individual residues or saturation mutagenesis remains labor- and time-intensive for entire proteins and simply is not possible on reasonable timescales for editing of multiple proteins in parallel, such as metabolic pathways or multi-protein complexes, using standard methods.